The present invention relates to Multi-Path Routing technology, and more specifically, the present invention relates to a method and apparatus for managing a plurality of sessions in a Multi-Path Routing based network.
Multi-Path Routing technology, especially Equal Cost Multi-Path (ECMP) or Weighted Cost Multi-Path (WCMP) routing technology, may be widely used in dynamic routing protocol based Internet Protocol (IP) networks. The dynamic routing protocol may be classified as Interior Gateway Protocol (IGP) and Exterior Gateway Protocol (EGP). The Interior Gateway Protocol includes, for example, Open. Shortest Path First (OSPF) routing protocol, Intermediate System to Intermediate System (IS-IS) routing protocol, etc. The Exterior Gateway Protocol includes, for example, Border Gateway Protocol (BGP), etc.
In the Multi-Path Routing based IP network, there are multiple different links to the same destination address. An IP data packet may be routed to a destination node via at least one intermediate node by using one of the links. The connection between two nodes and the information exchange therebetween may be referred to as a session. When the IP network employs the ECMP or WCMP routing technology, the data packets may be transferred using the multiple links simultaneously, thus the transmission bandwidth may be increased, and the data transmission of the failed links may be backed up without time delay and packet loss.
FIG. 2 shows a diagram of a typical ECMP or WCMP routing based IP network. As shown in FIG. 2, the data traffic may reach the destination network from node 1 via a plurality of intermediate nodes. The node 1 may establish, a plurality of ECMP or WCMP sessions to the plurality of intermediate nodes, and these sessions are established on the individual link respectively. However, due to a topology problem of the IP network or a hardware or software problem of routers, it ray occur where some protocol interfaces or physical ports will fail and then be restored (a flapping of a link), which in turn will cause the flapping of the session. In the ECMP or WCMP routing based IP network, IP data traffic may use a plurality of ECMP or WCMP sessions simultaneously. Even if the flapping occurs in the ECMP or WCMP session, the IP data traffic will still use the flapped ECMP or WCMP session. Thus, when the flapping occurs in the ECMP or WCMP session, it may cause the loss of the IP data packets.
To reduce the loss of IP data packets, a trunk containing the multiple links may be used between the nodes in the IP network as shown in FIG. 2, for example. In this case, the ECMP or WCMP session may be maintained as long as one link is available. However, in some cases, the data packets will still be lost, if the trunk fails or is being blocked, the loss of the data packets will occur. Furthermore, if the IP data traffic is mapped to an unstable link in the trunk via a hash algorithm, when the flapping occurs in the unstable link, there will also be the flapping in the ECMP or WCMP session, thereby resulting in the loss of data packets.